Erosion resisting fan wheel



Sept. 29, 1953 E, KRUHM|N EROSION RESISTING FAN WHEEL Filed June 26,1952 Patented Sept. 29, 1953 2,653,755 n EROSION RESISTING FAN WHEELErnest Kruhmin, Hyde Park, Mass., assigner to Westinghouse ElectricCorporation, East Pittsburgh, Pa., a corporation of PennsylvaniaApplication June 26, 1952, Serial No. 295,665

(Cl. 23o-134) 3 Claims.

This invention relates to centrifugal fans of the induced draft typewhich handle gases containing abrasive particles.

In steam power plants, induced draft fans handle large volumes of iluegases travelling at high velocities. Such iiue gases contain cinders andfly ash which are abrasives and which erode the fan blades. For limitingsuch erosion it has been the practice to cut out portions of the centerplates of the wheels of double inlet fans adjacent the advancing sidesof the fan blades. and to provide liners on the fan blades which can beremoved after a period of use, as disclosed in the T. B. AllardicePatent No. 2,287,853.

Such a construction has been successful in protecting the main surfacesof the fan blades, but experience has shown that severe erosion occursin the fan blades where they are attached to the center plates, and inthe liners adjacent the same areas. The blades have flanges, sec tionsof which extend perpendicular to corresponding sections of the mainblade portions, and which are riveted to the center plates. Smallcrevices occur between the center plates and the flanges where thelatter extend outwardly from the center plates, along the total lengthof the flanges. Such crevices extend throughout their lengths in thesame general direction as the abrasive laden gas passing through the fanwheels so that the abrasives enter the crevices and progressively widenthem by eroding the adjacent portions of the center plates and the bladeilanges, until the blades have to be replaced. This same action occurswhere the liners pass over the center plates and the blade anges sincethere are small clearance spaces between the liners, the center platesand the blade flanges, into which the abrasive material can enter. Theheads of the rivets which attach the blade flanges to the center plateare also eroded.

This invention prevents such erosion by providing slots in the centerplates inwardly of the inner ends of the blade flanges, and by providingin such slots wearing plates which extend across the path of the gaswhich would otherwise enter such crevices and clearance spaces, andwhich otherwise would pass over the heads of the rivets which attach theblade flanges to the center plate.

An object of this invention is to prevent abradouble inlet fan having acenter plate to which the fan blades are attached, from eroding theblades and the center plate at the center plate.

Another objechof the invention is to prevent in a double inlet fan wheelhaving a center plate to which the fan blades are attached, and havingprotective liners on the blades which pass across the center plate,abrasive particles carried by a gas through the wheel, from eroding thecenter plate, the blades and the liners adjacent where the blades areattached to the center plate.

The invention will now be described with reference to the drawing, ofwhich:

Fig. 1 is a side elevation, with a portion broken away, of a fan wheelembodying the invention;

Fig. 2 is a sectional view along the lines 2-2 of Fig. 1;

Fig. 3 is an enlarged fragmental view of the center plate of Figs. l and2, with one blade, one liner and one protective plate shown, and

Fig. 4 is a sectional view along the lines 4-4 of Fig. 3.

The hub 9 on the shaft IQ has attached thereto by spot welding, thecenter plate I 2 and its braces I3 and I4. The center plate is cut awayin front of the advancing side of each blade for providing thesubstantially V-shaped openings II which permit the oppositely directedstreams of gas from the two inlets of the wheel, to impinge upon eachother except where the blades are attached to the center plate. Theblades I5 have the flanges I6 which are riveted at I1 to portions of thecenter plate between the openings II, and which are riveted at I 8 tothe inlet plates I9, the latter being welded at 20 to the inlet rings 2I.

The Wheel illustrated is designed to rotate in a counterclockwisedirection with reference to Figs. l and 3 of the drawings, the blades I5being of the backwardly inclined, forwardly curved type. The liners 22are riveted at 23 to the advancing sides of the blades, and are shown atthe center of the wheel where erosion of the main working surfaces ofthe blades is most severe, but could be used to cover all of the mainworking surfaces. The liners 22 have the portions 24 which are bent overacross the inner edgesy of the blades I5 which aid in supporting theblades against the strains developed by centrifugal force. The linerportions 24 are notched at 25 to clear the center plate and the bladeanges I6.

The construction described so far with reference to the drawings, isconventional and is essentially that disclosed in said Allardice patent.

It will be noted with reference to Fig. 4 of the drawings, that thereare crevices 26 between the 3 anges I6 and the center plate I2 where theblades are bent outwardly perpendicular to these anges, such crevicesbeing unavoidable in quantity production because of the tendency of bentsheet metal to have rounded bends. It will also be noted that there areclearances 21 between the liner 22 and the center plate where the lineris notched. SuchA crevicesand clearances are in the path of abrasives inthegas moved by theblades, which abrasives work their way into thecrevices and clearance spaces and by erosion, enlarge the crevices untilsucient of the blades and. center plate is eroded away to requirereplacement. The' heads of the rivets l1 are in the-gas streamand.

are subject to erosion.

This invention prevents such. erosion by pro-- viding the slots 28 inthe center. plate I2. at the apices of the V-shaped openings' l'l`, oneside of each slot being a continuation* of a straight back edge 29 of anopening Il, and the other side of the. slot being parallel to said.. oneside thereof, at the inlet edge or" the associated fan blade. A wearing,plate 35. having arr outer portion 3| turned-over the follow theoutlinevof, and. to lie against, the inner portion of a. liner 22 isplaced in each of the. slots 23. Eachi plate is welded at 32 to a liner22, and at 33. to an edgeofa slot 23'.

Such wearing plates extend across the inner or inletends of the crevices2 and Z6 and provide barriers preventing entry of any abrasive materialinto. the crevices and clearance spaces, and from contacting the headsof the rivets Il..

By eliminating the erosion of the center plates of fan wheelaof the fanblades where they are attached to the center plates andof the rivetswhich attach the blades to the center plates, the lives of fan wheelshandling gases containing brasive particles, are greatly extended.

While one embodiment of the invention has been described for thepurposeof illustration,. it' should be understood that the invention is.not limited to the exact apparatus and arrangement of' apparatusdescribed, since modiiications thereof may be suggested by4 thoseskilled' in the art without departure from the essence of. theinvention.

What I claim as my invention, is:

i'. A fan wheel for a double inlet centrifugal' fan comprising a centerplate; said wheel having gas. inlet passages on opposite sides of the,enter platea plurality. of fan'olades around. said inlet passages; eachblade' having two sections with main working portions extending inalignment axially outwardly from opposite sides` of.

said center plate, and with flanged inner portions attached to saidcenter plate behind the main working portions; said center plate havingportions removed at the front sides ci said blades for providingopenings for permitting the oppositely flowing streams of gas moved bysaid blades to impinge, said center plate having slots extending fromsaid openings past the edges of said blades' nearest said passages, andprotective plates having portions in said slots and having portionsextending from said slots into said openings past Said blade edges forpreventing abrasiveparticles'in the gas from said passages from enteringthe spaces between said center plate and; said blades where said mainworking portions join said flanged portions.

2. A fan wheel for a double inlet centrifugal fan comprising' a centerplate; said wheel having gasf inlet passages on opposite sides of thecenter plate, a plurality of fan blades around said. inlet passages;suchblade having two sections with. main working portions extending inalignment axially outwardly from opposite sides of said center plateandwith iianged inner portions. attached to said center plate behind themain working portions; said center plate having, portions removed at thefront sides of said blades for providing openings for permitting theoppositelyv flowing streams of gas moved by said blades to impinge;protective liners on the front sides of said blades common to both bladesections andv extending across said center plate adjacent where saidhanged blade portions are attached to. said center plate; said centerplate having slots extending from said openings past the edges of saidblades nearest said passages, and protective plates having portions insaid slots and having portions extending from said slots into said.openings past said blade edges and said liners for preventing abrasiveparticles in the gas from said passages from entering the spacesbet-Weensaid center plate and said blades where. said main workingportions join said il'anged portions, and from entering the spacesbetween said center plate and said liners where saidv liners cross saidcenter plate.

3;.A fanwheel as claimed in claim 2 in which the, portions of saidprotective plates extending. from said slots into said openings pastsaid blade edges and said liners, have portions bent over against saidliners.

ERNEST KRUHMIN.

No references cited.

